Use of low-power RF energy for tissue diagnosis

ABSTRACT

The embodiments described herein relate to devices, systems and methods for in-vivo diagnosis of disease-state tissue within a body.

STATEMENT OF RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 62/306,441, filed Mar. 10, 2016 and entitled “USE OF LOW-POWER RFENERGY FOR TISSUE DIAGNOSIS”, which is hereby incorporated by reference.

FIELD OF THE DISCLOSURE

Embodiments described herein relate to devices, systems and methods forin-vivo diagnosis of disease-state tissue within a body, for example,within a passageway within a body. In particular, embodiments of thepresent disclosure relate to devices, systems and methods for diagnosingtissue by delivering low power radiofrequency energy to tissue within abody and monitoring, for example, a reflected portion of the energydelivered to the tissue during the tissue diagnosis procedure.

BACKGROUND OF THE DISCLOSURE

There are currently many methods of detecting disease-state tissuein-vivo. Various methods rely on some sort of imaging principle toidentify suspect areas for subsequent biopsy or treatment. Currentmethods have varying degrees of success rate and complexity. Acompounding factor in disease state tissue detection, particularly insmall passageways, is that the tissue is often difficult to visualize inhigh-definition because the imaging system is often too small to supporthigh definition cameras. Furthermore, disease state tissue can lie belowthe surface (e.g., the submucosa) making direct visualizationimpossible.

SUMMARY

Embodiments of the present disclosure include those directed to devices,systems and methods for diagnosing disease-state tissue within a body,for example, within a passageway within a body.

In various aspects, the present disclosure pertains to a method fordiagnosing tissue in a body, for example, within a passageway within abody. The method comprises: (a) positioning a medical device adjacent adiagnosis site adjacent the tissue, the medical device comprising (i) anelongate member having a proximal end and a distal end and (ii) anenergy emitting portion comprising at least one electrode adjacent thedistal end; (b) supplying an amount of low-power RF energy from anenergy source to the energy emitting portion to diagnose tissue at thediagnosis site, a first portion of the amount of low-power RF energybeing transmitted through the energy emitting portion to the tissue anda second portion of the amount of low-power RF energy being reflectedback towards the proximal end of the elongate member (with the firstportion and second portion each representing a percentage of the amountof low-power RF energy that is supplied); and (c) monitoring a signalcorresponding to the second portion.

In certain embodiments, which can be used in conjunction with any of theabove aspects, the power of the second portion, the voltage of thesecond portion, or both the power and voltage of the second portion maybe measured.

In certain embodiments, which can be used in conjunction with any of theabove aspects and embodiments, the method further comprises monitoring asignal corresponding to the first portion.

In certain embodiments, which can be used in conjunction with any of theabove aspects and embodiments, the method further comprises expandingthe energy emitting portion from a collapsed configuration to anexpanded configuration such that the at least one electrode contactstissue.

In certain embodiments, which can be used in conjunction with any of theabove aspects and embodiments, the method further comprises advancingthe energy emitting portion along a passageway in the body. In suchembodiments, the signal may be, for example, monitored continuously asthe energy emitting portion is advanced along the passageway ormonitored at a plurality of discrete positions along the passageway.

In certain embodiments, which can be used in conjunction with any of theabove aspects and embodiments, the signal may be monitored for each of aplurality of electrodes. In certain such embodiments, the monitoredsignal may be, for example, compared to a threshold value, compared to asignal monitored for another electrode, and/or compared to a baselinesignal based on a collection of electrodes.

In certain embodiments, which can be used in conjunction with any of theabove aspects and embodiments, the low-power RF energy may have anenergy level that is sufficiently high for diagnosis, while beingsufficiently low to avoid tissue damage.

In certain embodiments, which can be used in conjunction with any of theabove aspects and embodiments, the low-power RF energy may have anenergy level ranging from 0.1 dBm or less to 20 dBm or more, forexample, ranging from 0.1 to 0.2 to 0.5 to 1 to 2 to 5 to 10 to 20 dBm(i.e., ranging between any two of the preceding values).

In various aspects, the present disclosure pertains to a system fordiagnosing tissue within a body, for example, tissue of a passagewaywithin a body. The system may comprise: (a) an energy source; (b) amedical device configured to deliver energy to a diagnosis site adjacentthe tissue, the medical device comprising (i) an elongate member havinga proximal end and a distal end and (ii) an energy emitting portioncomprising at least one electrode adjacent the distal end of theelongate member, the medical device being configured to receive anamount of low-power RF energy from the energy source and to transmit afirst portion of the amount of low-power RF energy through the energyemitting portion to adjacent tissue; (c) one or more componentsconfigured to detect at least a signal corresponding to a second portionof the amount of low-power RF energy that is reflected back towards theproximal end of the elongate member; and (d) a controller configured toanalyze the signal to determine the state of diagnosis.

In certain embodiments, the one or more components may comprise abi-directional coupler that is configured to detect a signalcorresponding to the first portion of the amount of low-power RF energyand the signal corresponding to the second portion of the amount oflow-power RF energy.

In certain embodiments, which can be used in conjunction with any of theabove aspects and embodiments, the energy source may comprise alow-power RF generator.

In certain embodiments, which can be used in conjunction with any of theabove aspects and embodiments, the energy emitting portion may comprisea plurality of electrodes.

In certain embodiments, which can be used in conjunction with any of theabove aspects and embodiments, the energy emitting portion may comprisean expandable member upon which the electrodes are positioned.

In certain embodiments, which can be used in conjunction with any of theabove aspects and embodiments, the expandable member may comprises anexpandable frame and/or an expandable balloon upon which the electrodesare positioned. The electrodes may be positioned, for example, around acircumference of the expandable member, for instance, equally spacedaround a circumference of the expandable member.

In certain embodiments, which can be used in conjunction with any of theabove aspects and embodiments, the electrodes may be elongatedelectrodes that extend lengthwise along the expandable member. Forexample the elongated electrodes may have a (length-to-width) aspectratio ranging from 2:1 to 5:1 to 10:1 to 20:1 or more.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a system for diagnosing tissue ina passageway within a body, the system including a low powerradiofrequency energy delivery device having an energy emitting portion,according to an embodiment of the present disclosure.

FIG. 2 is a schematic side view of the energy emitting portion of FIG.1, according to an embodiment of the present disclosure.

FIG. 3 is an exploded view of a portion of a leg of the energy emittingportion of FIG. 2, according to an embodiment of the present disclosure.

FIG. 4 is a schematic perspective view of an energy emitting portion,according to another embodiment of the present disclosure.

FIG. 5 is a schematic perspective view of an energy emitting portion,according to yet another embodiment of the present disclosure.

FIG. 6 is a schematic diagram of the system of FIG. 1, according to anembodiment of the disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments of thepresent disclosure, examples of which are illustrated in theaccompanying drawings. Whenever possible, the same reference numberswill be used throughout the drawings to refer to same or like parts.

Generally described, the present disclosure relates to devices, systemsand methods for diagnosing tissue by delivering low-power radiofrequency(RF) energy to tissue with a body, more typically, to tissue within thewall of a passageway in a patient's body and monitoring reflected poweror voltage. “Passageway” as used herein refers to and includes anylumen, duct, cavity, space, or like within the body. Exemplarypassageways include the esophagus, colon, common bile duct, pancreaticduct and blood vessels, among others. In this regard, the presentdisclosure is directed to the detection of disease-state tissue, forexample, cancer tissue, through a low-power RF technique for in-vivodiagnosis in which changes in tissue impedance are detected by measuringchanges in reflected power of a low-power RF signal during a scan.

In certain embodiments, the low-power RF energy may have a low-powerenergy level that is sufficiently high for diagnosis, while beingsufficiently low to avoid tissue damage.

In certain embodiments, the low-power RF energy may have a low-powerenergy level ranging from 0.1 dBm or less to 20 dBm or more, forexample, ranging from 0.1 to 0.2 to 0.5 to 1 to 2 to 5 to 10 to 20 dBm(i.e., ranging between any two of the preceding values).

In this regard, impedance refers to an opposition to the flow ofelectrical current through the tissue. Reflected power is a function ofthe impedance mismatch between an RF signal generator (e.g., acontroller) and a load (e.g., tissue).

Radio frequency (RF) as defined herein is any of the electromagneticwave frequencies that lie in the range of 3 kHz-300 GHz. RF energydelivered in accordance with the present disclosure may be selected fromany portion of this range, for example, ranging from 3 kHz to 10 kHz to30 kHz to 100 kHz to 300 kHz to 1 MHz to 3 MHz to 10 MHz to 30 MHz to100 MHz to 300 MHz to 1 GHz to 3 GHz to 10 GHz to 30 GHz to 100 GHz to300 GHz (i.e., ranging between any two of the preceding values). Incertain embodiments, the range selected may optimized based on a tissuepenetration depth of less than 1 cm. In certain embodiments, thefrequency range of 1 MHz to 300 MHz may be less desirable due topotential ablation effects.

The power delivered to a load by an RF signal, P_(load), often expressedin units of dB (decibels) or dBm (decibel milliwatts), is defined as:

${P_{load} = \left\lbrack {\frac{{V_{f}}^{2}}{Z_{0}} - \frac{{V_{r}}^{2}}{Z_{0}}} \right\rbrack},$where V_(f) is forward voltage, V_(r) is the reflected voltage, and Z₀is the transmission line impedance. In general, power with respect tovoltage is defined as:

$P = {\frac{{V}^{2}}{Z_{0}}.}$

Therefore, the power delivered to a load is a function of both forwardand reflected power. As reflected power increases, the power deliveredto load decreases. Reflected voltage (and reflected power) increase dueto impedance mismatches between the RF signal generator and load asdefined by:

${V_{r} = \frac{V - \left( {Z_{0} \cdot I} \right)}{2}},$where V is source voltage and I is source current. For V=Z₀I,V_(r)=P_(r)=0 and therefore the power delivered to the load will beequal to P_(f), where P_(f) is forward power.

Biological tissue possesses a characteristic impedance depending uponits molecular composition. For instance, it is understood that canceroustissue generally possesses a lower characteristic impedance compared tothat of healthy tissue of the same type. Other disease states are alsoexpected to have impedance differences compared to healthy tissue.

Consequently, a controller may be tuned such that the transmission lineimpedance is similar to that of healthy tissue associated with thediagnosis site, resulting in small amounts of reflected power. In thisregard, the impedance of the transmission line, which includes thesignal path from generator to the probe, should be well understood andin some embodiments, may be tuned to the match the load anticipated forhealthy tissue. A transmission line tuned to have impedance equal to thetissue load will result in minimal (theoretically zero) reflected power.During diagnosis, tissue impedance changes will result in differences inreflected power, increasing impedance mismatch resulting in an increasein reflected power. A reflected power threshold may be identified toindicate a disease state. Methods based on is principle may allow fordetection below the visible surface, and for mucosa-lined passageways,may improve detection within the submucosa.

In the present disclosure an RF probe including one or more electrodesand an RF controller including an RF generator, may be used as adiagnostic system. The RF probe may be re-usable or disposable. Incertain embodiments, the system may further include a catheter (i.e., atube, including vascular catheters, endoscopes, etc.), which may bere-usable or disposable, and which may be provided in various sizesdepending on the anatomy intended to be analyzed. The catheter may beprovided with visualization to guide the physician and may be providedwith a working channel through which the RF probe may be passed.

In this regard, the RF probe may be passed through the catheter to thedistal tip. A health care professional can then pass the probe over theanatomy. For improved accuracy, the probe preferably stays in contactwith tissue while at the same time being atraumatic. The RF controllermay be configured to deliver low-power RF energy, typically an energylevel that is sufficiently high for diagnosis, while being sufficientlylow to avoid tissue damage (e.g., maintaining cells of tissue beingdiagnosed to 40° C. or less), to the probe. The RF controller may alsobe configured to control the electrode state, delivering RF energy tothe active electrode(s) at the tissue interface and measuring reflectedpower from the tissue. Algorithms may be used to control the electrodestate with respect to time.

Turning now to the drawings, FIG. 1 illustrates an exemplary system 10.System 10 includes an energy generator 12, a controller 14, a userinterface 16, and a probe 18. Energy generator 12 may be any suitabledevice configured to produce low-power RF energy for diagnosing tissueas described herein. The RF energy generator may be configured to emitenergy at specific frequencies and for specific amounts of time.

More particularly, energy generator 12 may be configured to generateenergy with a wattage output sufficient to diagnose tissue withoutharming (ablating) the tissue.

An energy controlling mechanism 22 may be associated with energygenerator 12. Energy controlling mechanism 22 may be any suitableautomatic and/or user operated device in operative communication withenergy generator 12 via a wired or wireless connection, such that energycontrolling mechanism 22 may be configured to enable activation ofenergy generator 12. Energy controlling mechanism 22 may thereforeinclude a switch, a push-button, or a computer, among otherpossibilities. In the exemplary embodiment of FIG. 1, energy controllingmechanism 22 is a footswitch. A conductive cable 24 may extend fromenergy controlling mechanism 22 to user interface 16, and may include acoupler 24 a configured to be electrically coupled to an interfacecoupler 26 disposed on user interface surface 16.

Controller 14 may be coupled to energy generator 12. Controller 14 mayinclude a processor 20 configured to produce signals for controlling theenergy generator 12, receive information feedback signals (e.g.,reflected signals), process the information feedback signals accordingto various algorithms, and produce signals directed to visual and/oraudio indicators. For example, processor 20 may include one or moreintegrated circuits, microchips, microcontrollers, and/ormicroprocessors, which may be all or part of a central processing unit(CPU), a digital signal processor (DSP), an analog processor, a fieldprogrammable gate array (FPGA), or any other circuit known to thoseskilled in the art that may be suitable for executing instructions orperforming logic operations. That is, processor 20 may include anyelectric circuit that may be configured to perform a logic operation onat least one input variable. In some embodiments, processor 20 may beconfigured to use a control algorithm to analyze a reflected portionand/or a forward portion of the energy delivered to targeted tissue andgenerate control signals for energy generator 12.

Controller 14 may additionally be coupled to and in communication withuser interface 16. In the exemplary embodiment illustrated in FIG. 1,controller 14 may be electrically coupled to user interface 16 via awire connection. In alternative embodiments, controller 14 may be inwireless communication with user interface 16. User interface 16 may beany suitable device capable of providing information to an operator ofthe energy delivery system 10. Accordingly, user interface 16 may beconfigured to be operatively coupled to each of the components of energydelivery system 10, receive information signals from the components, andoutput at least one visual or audio signal to a device operator inresponse to the information received. In the exemplary embodiment, thesurface of user interface 16 includes at least one switch 36 and adisplay 38. It is contemplated that user interface 16 may additionallyinclude one or more audio tone indicators and/or graphicalrepresentations of components of system 10.

Probe 18 may be coupled to user interface 16. For example, a cable 40may extend from probe 18 to user interface 16, and include a coupler 40a configured to be electrically coupled to an interface coupler 42associated with user interface 16.

Probe 18 may include a handle portion 44, an elongate member 46, and anenergy emitting portion 48. In certain embodiments, one or more of theuser interface 16, controller 14 and energy generator 12 may beintegrated into the handle portion 44. Elongate member 46 has a proximalend 46 a and a distal end 46 b. As used herein, “proximal” refers to theend closer to the device operator during use, and “distal” refers to theend further from the device operator during use. Thus, handle portion 44may be disposed at proximal end 46 a of elongate member 46 and energyemitting portion 48 may be disposed at distal end 46 b. Handle portion44 may be any suitable handle and may have one or more actuators,switches, or the like to control movement of elongate member 46 and/ormanipulate energy emitting portion 48.

Elongate member 46 extends distally from handle portion 44. Elongatemember 46 may be a flexible tube, made from any suitable biocompatiblematerial having sufficient flexibility to traverse non-linear anatomy.Such materials may include, but are not limited to, rubber, silicon,other polymers, metal-polymer composites, metals including metal alloysof one or more of nickel, titanium, copper cobalt, vanadium, chromium oriron (e.g., stainless steel), superelastic material such as nitinol,which is a nickel-titanium alloy.

Elongate member 46 and energy emitting portion 48 may be provided with acoating. The coating may be any coating known to those skilled in theart enabling ease of movement of probe 18 through an access device suchas a catheter and/or a passageway within a patient's body. The coatingmay include a lubricious coating and/or an anesthetic.

As indicated above, in some embodiments, system may further include acatheter 80 (represented by dashed lines) that includes an elongatemember with one or more lumens or channels formed therein for thepassage of a variety of surgical equipment, including, but not limitedto, probe 18, imaging devices and tools for irrigation, insufflation,vacuum suctioning, biopsies, and drug delivery. The catheter may includean imaging device mounted at the distal end of the catheter. Thecatheter may include an atraumatic exterior surface having a roundedshape and/or a coating like that described above.

Energy emitting portion 48 may be attached to and extend from distal end46 b of elongate member 46. Energy emitting portion 48 may be formedfrom the same piece of material as elongate member 46. Alternatively,energy emitting portion 48 may be fabricated independently of elongatemember 46 by any known means and may be made permanently or removablyattached to distal end 46 b of elongate member 46. For example, energyemitting portion 48 may be permanently or removably attached to distalend 46 b of elongate member 46 via a flexible junction enabling movementof energy emitting portion 48 relative to distal end 46 b of elongatemember 46.

Referring to FIG. 2, energy emitting portion 48 may be any size, shapeand/or configuration having dimensions that can be inserted into apassageway within a body and advanced to a diagnosis site 60. In theembodiment shown, energy emitting portion 48 may comprise an expandableframe that is configured to be advanced to the diagnosis site in afirst, collapsed configuration (not shown) whereupon it takes on asecond, expanded configuration as shown once positioned at a diagnosissite 60 in a passageway. For example, the expandable frame may beadvanced to the diagnosis site 60 within a catheter at which point theexpandable frame is advanced relative to the catheter and/or thecatheter is retracted relative to the expandable frame, such that theexpandable frame extends beyond a distal end of the catheter. In someembodiments, the frame has a shape memory and is maintained in a first,collapsed position by walls of the catheter and subsequently expands toa second, expanded configuration at the diagnosis site 60 when freedfrom the catheter as a result of the shape memory. In other embodiments,one or more actuators, which may be operated from the handle portion 48,may be used to lengthen the frame during advancement in a first,collapsed configuration, after which the frame may subsequently beexpanded into a second, expanded configuration at the diagnosis site 60,for example, by providing the frame with a shape memory effect thatcauses the frame to radially expand or by using the actuator to shortenlength of the frame, thereby causing the frame to radially expand. Instill other embodiments, the energy emitting portion 48 may comprise anexpandable balloon is configured to be advanced to the diagnosis site 60in a first, collapsed state and take on a second, expanded configurationby inflating the balloon once positioned at a diagnosis site 60 in apassageway. Once in a second, expanded configuration, a contact region50 of energy emitting portion 48 may be configured to contact tissue atdiagnosis site 60.

Energy emitting portion 48 may have any shape, size, and/orconfiguration in the second, expanded configuration. In the exemplaryembodiment shown in FIG. 2, energy emitting portion 48 comprises ahaving a plurality of curved legs 52 that converge at a distal tip 53.Also shown is an actuation rod 57 for lengthening and shortening theframe. Legs 52 may be configured so that the legs 52 correspond to linesdrawn along a surface of an imaginary prolate spheroid (represented byshaded area) in the second, expanded configuration. In this embodiment,region 50 may be the portion of frame that is the greatest distance fromthe longitudinal axis of energy emitting portion 48 when energy emittingportion 48 is in the second, expanded configuration. It is contemplatedthat legs 52 may form any other shape and/or configuration thatfacilitates contact between contact region 50 and tissue of diagnosissite 60 in the second, expanded configuration.

Legs 52 may be constructed from a material such as, for example, a shapememory metal or metal alloy or a polymeric material so that legs 52 maycollapse to have a smaller cross-section in the first, collapsedconfiguration (not shown). Although FIG. 2, shows that that energyemitting portion 48 comprises four legs 52, energy emitting portion 48may include any number of legs 52 (e.g., 2, 3, 5, 6, 7, 8, etc. legs)having any desired pattern and/or configuration. For example, legs 52may correspond to a surface of an imaginary cylinder or any othersuitable shape. In addition, legs 52 may have any cross-sectional shapeincluding, but not limited to, circular, square, or ovular.

Energy emitting portion 48 may further include at least one electrode56. The at least one electrode 56 may be located along the length of atleast one of the plurality of legs 52 and may include at least a portionof the contact region 50 of energy emitting portion 48. In the exemplaryembodiment illustrated in FIG. 3, the at least one leg 52 of the energyemitting portion 48 comprises a single, elongate conducting element,portions of which may be covered by an insulating material 54, such as,for example, a non-conducting polymeric sheath that is heat shrunk ontoeach leg 52. In addition, another portion of the elongate conductingelement disposed between the insulated portions 54 is exposed, formingan electrode 56 for delivering energy to tissue at diagnosis site 60.The electrode 56 may be, for example, any suitable electrode known tothose skilled in the art configured to emit RF energy. In the embodimentof FIG. 2, four electrodes 56 a, 56 b, 56 c, 56 d are shown. Theelectrodes 56 a, 56 b, 56 c, 56 d may be operated in monopolar mode orbipolar mode.

In embodiments where energy emitting portion 48 includes monopolarelectrodes 56 a, 56 b, 56 c, 56 d, system 10 further includes a returnelectrode component configured to complete an electrical energy emissionor patient circuit between energy generator 12 and a patient (notshown). Referring to FIG. 1, the return electrode component may includea conductive pad 28 for this purpose. Conductive pad 28 may include aconductive adhesive surface configured to removably adhere to apatient's skin. In addition, conductive pad 28 may include a surfacearea having a sufficient size in order to alleviate burning or otherinjury to the patient's skin that may occur in the vicinity of theconductive pad 28 during energy emission. A cable 30 may extend fromconductive pad 28 and may include a coupler 30 a. Coupler 30 a may beconfigured to be coupled to an interface coupler 32 on a surface of userinterface 16 to electrically couple conductive pad 28 to the userinterface 16.

In other embodiments, electrodes 56 a, 56 b, 56 c, 56 d may be operatedin bipolar mode, in which case a separate return electrode component(e.g., conductive pad) is not required, but which may nonetheless beprovided in the event that it is also desired to operate the electrodes56 a, 56 b, 56 c, 56 d in monopolar mode. With regard to bipolar mode,for example, electrode 56 a may be operated as an active electrode whileelectrode 56 b is simultaneously operated as a return electrode, afterwhich electrode 56 a may be operated as a return electrode whileelectrode 56 b is simultaneously operated as an active electrode.Similarly, electrode 56 c may be operated as an active electrode whileelectrode 56 d is simultaneously operated as a return electrode, afterwhich electrode 56 c may be operated as a return electrode whileelectrode 56 d is simultaneously operated as an active electrode. Inother words, electrodes 56 a, 56 b are operated as a first bipolar pairand electrodes 56 c, 56 d are subsequently operated as a second bipolarpair.

As another example, electrodes 56 a and 56 c may be operated as activeelectrodes while electrodes 56 b and 56 d, respectively, aresimultaneously operated as return electrodes for electrodes 56 a and 56c, respectively, after which electrodes 56 a and 56 c may be operated asreturn electrodes while electrodes 56 b and 56 d, respectively, aresimultaneously operated as active electrodes. In other words, electrodes56 a, 56 b and electrodes 56 c, 56 d are simultaneously operated asfirst and second bipolar pairs.

More broadly, the electrodes may be operated as the following bipolarpairs: electrodes 56 a, 56 b, electrodes 56 a, 56 c, electrodes 56 a, 56d, electrodes 56 b, 56 c, electrodes 56 b, 56 d, and electrodes 56 c, 56d.

In FIG. 2, the electrodes are placed on an expandable frame thatcomprises a plurality of legs 12 as structural support members for theelectrodes. In another embodiment shown in FIG. 4, an energy emittingportion 48 is shown in which the expandable electrodes placed on asurface of an expandable balloon 55. In the example shown, threeelectrodes, 56 a, 56 b, 56 c (out of six total electrodes) are shown,which extend longitudinally along a length of the balloon, althoughenergy emitting portion 48 may include any number of electrodes (e.g.,2, 3, 4, 5, 7, 8, etc.) having any desired pattern disposed on theballoon. As in FIG. 2, the electrodes may be operated in monopolar modeor bipolar mode. For example, a balloon formed from a material such aspolyimide or polyethylene terephthalate may be patterned with goldelectrodes, for example, using processes like those described in U.S.Patent Pub. No. 2014/0128859. Because the electrodes are disposed aroundthe balloon, a scan may be made around a circumference of the energyemitting portion 48, and the balloon need not be rotated inside thelumen.

While the energy emitting portion 48 of FIG. 2 includes one electrode 56per leg. In other embodiments, a plurality of electrodes is providedalong a length of each leg. With reference now to FIG. 5, an energyemitting portion 48 is shown in which three electrodes are located alongthe length of at least one of the plurality of legs 52 (an analogousdistribution of electrodes could be created on a balloon surface). Dueto the fact that the outermost radial portions of the legs 12 linear,the contact region 50 of the energy emitting portion 48 is significantlylonger than that of FIG. 2. Twelve electrodes 56 a, 56 b, 56 c, 56 d, 56e, 56 f, 56 g, 56 h, 56 i, 56 j, 56 k, 56 l are shown. As in FIG. 2, theelectrodes 56 a, 56 b, 56 c, 56 d, 56 e, 56 f, 56 g, 56 h, 56 i, 56 j,56 k, 56 l may be operated in monopolar mode or bipolar mode.

In one specific example, among other possibilities, the followingelectrodes may be operated as bipolar pairs at a given longitudinalposition on the energy emitting portion 48: (a) adjacent electrodes 56a, 56 b, electrodes 56 b, 56 c, electrodes 56 c, 56 d and electrodes 56d, 56 a, as well as non-adjacent electrodes 56 a, 56 c and electrodes 56b, 56 d, (b) adjacent electrodes 56 e, 56 f, electrodes 56 f, 56 g,electrodes 56 g, 56 h and electrodes 56 h, 56 e, as well as non-adjacentelectrodes 56 e, 56 g and electrodes 56 f, 56 h, (c) adjacent electrodes56 l, 56 j, electrodes 56 j, 56 k, electrodes 56 k, 56 l and electrodes56 l, 56 i, as well as non-adjacent electrodes 56 i, 56 k and electrodes56 j, 56 l. In this way, a scan may be made around a circumference ofthe energy emitting portion 48 at three different longitudinal positionsalong the energy emitting portion 48 without moving the energy emittingportion 48.

In another specific example, among other possibilities, the followingelectrodes may be operated as bipolar pairs at a given angular positionon the energy emitting portion 48 (i.e., a given angle of rotationaround the longitudinal axis of the on the energy emitting portion 48):(a) electrodes 56 i, 56 e, electrodes 56 e, 56 a, electrodes 56 i, 56 a,(b) electrodes 56 j, 56 f, electrodes 56 f, 56 b, electrodes 56 j, 56 b,(c) electrodes 56 k, 56 g, electrodes 56 g, 56 c, electrodes 56 k, 56 c,(d) electrodes 56 l, 56 h, electrodes 56 h, 56 d, electrodes 56 l, 56 d.In this way, a length of tissue along the diagnosis site can be scannedwithout moving the energy emitting portion 48. In this way, a scan maybe made along the length of the energy emitting portion 48 at fourdifferent angles of rotation around the axis of the energy emittingportion 48 without moving the energy emitting portion 48.

FIG. 6 is a simplified representation of system 10. As will be describedbelow, components of system 10 may be configured to deliver energy totissue at diagnosis site 60 and to monitor a reflected portion of thatenergy.

With reference to FIG. 6, energy generator 12 of system 10 may becontrolled by controller 14, and may be configured to generate a forwardsignal for delivering energy to tissue at diagnosis site 60. Asdiscussed above, energy generator 12 may be an RF generator configuredto generate a forward RF signal. The forward RF signal may be carried tothe at least one electrode 56 in contact with tissue at diagnosis site60 via transmission line 58. Transmission line 58 broadly refers to anystructure or structures designed to carry alternating current of, forexample, radio frequency. In the exemplary embodiment, transmission line58 may include energy generator 12, the at least one electrode 56, andconducting elements therebetween including, but not limited to, cable40, and conductors within the elongate member 46 and energy emittingportion 48.

The forward RF signal carried via transmission line 58 may be suppliedto the at least one electrode 56. The at least one electrode 56 may thendeliver energy to tissue at diagnosis site 60. In particular, low-powerRF energy may be delivered through the electrode 56 in contact withtissue at diagnosis site 60 in order to analyze tissue at the diagnosissite.

As will be described in more detail below, system 10 may be configuredto analyze tissue at the diagnosis site 60 using a reflected portion ofthe energy delivered to the at least one electrode 56. The reflection ofenergy may be a function of the impedance of tissue at diagnosis site60.

As indicated above, when the impedance of transmission line 58 is tunedto match the impedance of the load (in this case comprising theimpedance of the tissue at diagnosis site 60), a substantial portion ofthe energy delivered via transmission line 58 may be transmitted throughthe at least one electrode 56 to tissue at diagnosis site 60. When theimpedance of the transmission line 58 and the impedance of the tissue atdiagnosis site 60 are not matched, a portion of energy supplied toelectrode 56 may be reflected back along transmission line 58 to energygenerator 12 via secondary signals. The secondary signals may havereflected power. As indicated above, having the ability to measurereflected power provides the possibility to monitor tissue impedance.

The magnitude of the reflected power may be proportional to the mismatchbetween the impedance of transmission line 58 and the impedance oftissue at diagnosis site 60. That is, the magnitude of the reflectedpower may increase as the impedance of tissue at diagnosis site 60decreases from a matched impedance value during diagnosis. In addition,the net forward power, which is approximately equal to the differencebetween the forward power (associated with the forward signal) and thereflected power (associated with the secondary signal), may decrease.

The system 10 may be provided with ability to measure both forward andreflected power, with suitable methods and devices for doing sodetermined by one of ordinary skill in the art. As illustrated in FIG.6, system 10 may include a bi-directional coupler 62 for detecting thereflected power and the forward power of the primary RF signal carriedvia transmission line 58. Bi-directional coupler 62 may be positionedbetween energy generator 12 and the at least one electrode 56, and incommunication with energy generator 12 and the at least one electrode56. In some embodiments, bi-directional coupler 62 may be integrallyprovided with energy generator 12. In other embodiments, bi-directionalcoupler 62 may be a separate component placed between energy generator12 and the at least one electrode 56. As shown in FIG. 6, the primary RFsignal may be inputted to bi-directional coupler 62. The primary RFsignal may pass therethrough unaffected and may be outputted frombi-directional coupler 62 to be transmitted to the at least oneelectrode 56.

Bi-directional coupler 62 may be any known coupler configured to provideone or more signal sample outputs for measurement. In the exemplaryembodiment, bi-directional coupler 62 may be configured to sample theforward and reflected RF signal passing therethrough and detect theforward power and the reflected power. Bi-directional coupler 62 mayoutput a first signal 64 indicative of the forward power and a secondsignal 66 indicative of the reflected power to first monitoring device68 and second monitoring device 70, respectively.

First monitoring device 68 and second monitoring device 70 may be anyknown electrical component configured to measure a power signal. In someembodiments, one or both of first monitoring device 68 and secondmonitoring device 70 may be a power meter. First monitoring device 68and second monitoring device 70 may be in communication with processor20 either wirelessly or via a wired connection to transmit informationrelating to the forward power and the reflected power. In this manner,the forward and reflected powers may be measured in real time, andchanges in the net power level may be detected. Alternative known meansfor detecting and measuring the forward power and the reflective powerare also contemplated.

Prior to initiating the diagnosis procedure, controller 14 may beconfigured to tune transmission line 58 to have an impedance that isbased on that of healthy tissue at diagnosis site 60. For example, thetransmission line 58 may be tuned to have an impedance that issubstantially equal to the impedance of the healthy tissue at diagnosissite 60, which will result in a negligible amount of reflected power.The impedance of the healthy tissue may be well-known or may becalculated by any known means such as empirical data and/or clinicalmeasurements.

As diagnosis is initiated, probe 18 may be inserted into and advancedthrough a passageway within a patient's body to diagnosis site 60. Afterenergy emitting portion 48 has been positioned at diagnosis site 60,energy emitting portion 48 may be expanded from a first, collapsedconfiguration to a second, expanded configuration so that contact region50 is placed in contact with tissue at diagnosis site 60.

Energy generator 12 may be continuously activated, or an operator mayengage energy controlling mechanism 22 to activate energy generator 12.Activation of energy generator 12 may generate a forward signal, forexample, a forward RF signal, for delivery through the least oneelectrode 56 of energy emitting portion 48 to tissue at diagnosis site.In particular, energy generator 12 may generate a forward signal thatmay be supplied to the at least one electrode 56 via transmission line58. The low-power RF energy supplied to the at least one electrode 56may be delivered to tissue at diagnosis site 60. Accordingly, a portionof the energy supplied to electrode 56 may be reflected back alongtransmission line 58 to energy generator 12 via secondary signals. Thesecondary signals have reflected power.

In various embodiments, the energy emitting portion 48 may then be movedlongitudinally within the passageway and the reflected power measuredcontinuously during movement or at a plurality of discrete positionsalong the passageway. As movement progresses, the magnitude of thereflected power may change (i.e., increase or decrease), indicating achange in tissue impedance and thus a change in tissue state. Where thetransmission line impedance is matched to that of healthy tissue, anincrease in reflected power may indicated the presence of diseased(e.g., cancerous) tissue.

Over the course of the diagnosis, bi-directional coupler 62 may beconfigured to sample the signal passing therethrough and output a firstsignal 64 indicative of forward power and a second signal 66 indicativeof reflective power to first monitoring device 68 and second monitoringdevice 70, respectively. In some cases, first signal 64 and secondsignal 66 may be proportional to the forward power and the reflectedpower of the forward signal, respectively.

In the exemplary embodiment, second monitoring device 70 maycontinuously monitor the second signal 66 corresponding to the reflectedpower. In particular, second monitoring device 70 may monitor secondsignal 66 to measure the magnitude of the reflective power. Secondmonitoring device 70 may then transmit the measured value to processor20.

Where the energy emitting portion 48 contains a plurality of electrodes,each electrode at a different angle of rotation around a longitudinalaxis of the energy emitting portion 48 (see, e.g., FIGS. 2 and 4), thereflected power may be analyzed from each electrode, either throughoperation in unipolar mode or bipolar mode, as each electrode isadvanced through the body passageway.

Processor 20 may analyze the magnitude of the reflected power or voltagefrom each electrode for changes in reflected power or voltage, whichwould indicate changes in tissue state as the energy emitting portion 48is moved along the passageway. For example, as previously noted it isunderstood that cancerous tissue possesses a lower characteristicimpedance compared to that of healthy tissue of the same type. Thus,where the transmission line 58 is tuned to have an impedance matchingthat of healthy tissue at diagnosis site 60, movement of an electrode 56from healthy tissue to cancerous tissue can cause an increase in thereflected power or voltage. In other embodiments, the transition fromhealthy tissue to diseased tissue may be reflected by a change inimpedance.

In various embodiments, processor 20 may be configured to monitor themagnitude of the reflected power or voltage signal as the energyemitting portion 48 is moved along the passageway. Any method of signalprocessing, including measuring the derivative of the reflected powersignal as a function of longitudinal movement (or time, assumingconstant longitudinal movement) can be used to detect a change in slopewhich reflects a tissue change.

In some embodiments, the magnitude of the reflected power and/or voltagesignal can be displayed to the operator, for example, via a screen.

In some embodiments, processor 20 may be configured to compare themagnitude of the reflected power or voltage signal to a pre-setthreshold to determine if the magnitude of the reflected power signalreaches or passes the pre-set threshold value. In those embodiments,operator may be notified when the magnitude of the reflected power orvoltage exceeds the threshold, which may indicate the presence ofdiseased tissue such as cancerous tissue.

In some embodiments, processor 20 may be configured to compare changesin the magnitude of the reflected power or voltage signal (e.g., apercent change) to a pre-set threshold value. In those embodiments,operator may be notified when the change in magnitude of the reflectedpower or voltage exceeds the threshold, which may indicate a change intissue state, for example, a change from healthy tissue to diseasedtissue such as cancerous tissue.

In some embodiments, the energy emitting portion 48 comprises a numberof electrodes 56 and remains stationary within the passageway as thereflected power associated with the individual electrodes 56 ismeasured, whereby allowing the passageway to be mapped without movingthe energy emitting portion 48. Analogous to the embodiments above, themagnitude of the reflected power may change (i.e., increase or decrease)change from one electrode 56 to another, indicating a change in tissueimpedance and thus a change in tissue state.

As in the embodiments above, bi-directional coupler 62 may be configuredto sample the signal passing therethrough and output a first signal 64indicative of forward power and a second signal 66 indicative ofreflective power to first monitoring device 68 and second monitoringdevice 70, respectively. For example, second monitoring device 70 maymonitor the second signal 66 corresponding to the reflected power ateach electrode position. In particular, second monitoring device 70 maymonitor second signal 66 to measure the magnitude of the reflected poweror voltage. Second monitoring device 70 may then transmit the measuredvalue to processor 20.

Processor 20 may analyze the magnitude of the reflected power or voltagefrom each electrode for changes in reflected power or voltage betweenelectrodes, which could indicate changes in the state of the tissueadjacent to the electrodes. For example, as noted above, it isunderstood that diseased tissue such as cancerous tissue generallypossesses a lower characteristic impedance compared to that of healthytissue of the same type. Thus, where the transmission line 58 is tunedto have an impedance similar to the healthy tissue at diagnosis site 60,the presence of cancerous tissue would be detected by an increased valuefor the reflected power or voltage.

In some embodiments, the magnitude of the reflected power or voltagesignal can be conveyed to the operator, for example, via a screen.

In some embodiments, processor 20 may be configured to compare themagnitude of the reflected power or voltage signal from each electrodeto a preset threshold to determine of the magnitude of the reflectedpower signal is greater than or equal to the pre-set threshold value,which may indicate the presence of diseased tissue such as canceroustissue in some cases. In those embodiments, the electrodes for which themagnitude of the reflected power signal is greater than or equal to thepre-set threshold value may be displayed to the operator, for example,via a screen.

In some embodiments, processor 20 may be configured to compare themagnitude of the reflected power or voltage signal to some baselinevalue for the reflected power or voltage signal (e.g., the averagereflected power and/or average reflected voltage). In those embodiments,each electrode for which the magnitude of the reflected power or voltagesignal is greater than baseline value by a predetermined amount (e.g.,by a predetermined percentage) may be displayed to the operator, forexample, via a screen.

In certain embodiments, reflected low-power RF energy may be analyzed todetermine if the at least one electrode 56 is in contact with the tissueat diagnosis site 60, as described in detail in U.S. Patent Pub. No.2013/0324995.

In certain embodiments, high-power RF energy may also be deliveredthrough the at least one electrode 56 in contact with tissue atdiagnosis site 60 in order to raise a temperature of the tissue to athreshold temperature that ablates or otherwise alters the targettissue. Such power may be applied based on the results of the tissueanalysis at low-power RF energy.

What is claimed is:
 1. A method for diagnosing disease-state tissue of a passageway in a body comprising: positioning a medical device in the passageway adjacent the tissue, the medical device comprising an energy emitting portion that comprises a plurality of electrodes positioned both around a circumference of the energy emitting portion and along a length of the energy emitting portion; supplying an amount of low-power RF energy from an energy source to the energy emitting portion to diagnose the tissue, a first portion of the amount of low-power RF energy being transmitted through the energy emitting portion to the tissue and a second portion of the amount of low-power RF energy being reflected back towards the medical device; monitoring a signal corresponding to the second portion for each of the plurality of electodes, wherein the second portion associated with individual electrodes is measured; and analyzing the signal to determine a presence or absence of said disease-state tissue.
 2. The method of claim 1, wherein the power of the second portion, the voltage of the second portion, or both the power and voltage of the second portion are measured.
 3. The method of claim 1, further comprising monitoring a signal corresponding to the first portion.
 4. The method of claim 1, further comprising expanding the energy emitting portion from a collapsed configuration to an expanded configuration such that the plurality of electrodes contact tissue.
 5. The method of claim 1, further comprising advancing the energy emitting portion along the passageway.
 6. The method of claim 5, wherein the signal is monitored continuously as the energy emitting portion is advanced, or wherein the signal is monitored at a plurality of discrete positions.
 7. The method of claim 1, wherein the signal monitored for each of the plurality of electrodes is compared to a threshold value.
 8. The method of claim 1, wherein the signal monitored for each of the plurality of electrodes is compared to a signal monitored for another of the plurality of electrodes or to a baseline signal based on a collection of electrodes.
 9. The method of claim 1, wherein the passageway is a mucosa-lined passageway and wherein submucosal tissue is diagnosed.
 10. The method of claim 9, wherein the plurality of electrodes are operated as bipolar pairs.
 11. The method of claim 10, further comprising moving the energy emitting portion longitudinally within the passageway, wherein the signal corresponding to the second portion is monitored continuously during movement and wherein the passageway is mapped.
 12. The method of claim 9, wherein the disease-state tissue is cancerous tissue.
 13. A system for diagnosing disease-state tissue of a passageway within a body, the system comprising: an energy source; a medical device configured to deliver energy to a diagnosis site in the passageway, the medical device comprising an elongate member having a proximal end and a distal end, and an energy emitting portion comprising a plurality of electrodes adjacent the distal end, the plurality of electrodes being positioned both around a circumference of the energy emitting portion and along a length of the energy emitting portion and being operable as bipolar pairs, the medical device being configured to receive an amount of low-power RF energy from the energy source, a first portion of the amount of low-power RF energy being transmitted through the energy emitting portion to the tissue and a second portion of the amount of low-power RF energy being reflected back towards the proximal end of the elongate member; one or more components configured to detect at least a signal corresponding to the second portion of the amount of energy; and a controller configured to analyze the signal to determine a presence or absence of said disease-state tissue.
 14. The system of claim 13, wherein the one or mom components comprise a directional coupler that is configured to detect a signal corresponding to the first portion of the amount of low-power RF energy and the signal corresponding to the second portion of the amount of low-power RF energy.
 15. The system of claim 13, wherein the energy source is a low-power RF generator.
 16. The system of claim 13, wherein the controller is configured to analyze the signal to map the passageway.
 17. A system for diagnosing disease-state tissue of a passageway within a body, the system comprising: an energy source; a medical device configured to deliver energy to a diagnosis site in the passageway, the medical device comprising an elongate member having a proximal end and a distal end, and an energy emitting portion adjacent the distal end comprising a plurality of electrodes disposed upon an expandable member, the plurality of electrodes being positioned both around a circumference of the expandable member and along a length of the expandable member and being operable as bipolar pairs, the medical device being configured to receive an amount of low-power RF energy from the energy source and to transmit a first portion of the amount of low-power RF energy through the energy emitting portion to the tissue; one or more components configured to detect at least a signal corresponding to a second portion of the amount of low-power energy that is reflected back towards the proximal end of the elongate member; and a controller configured to analyze the signal to determine a presence or absence of said disease-state tissue.
 18. The system of claim 17, wherein the plurality of electrodes are elongated electrodes that extend lengthwise along the expandable member.
 19. The system of claim 17, wherein the expandable member is an expandable frame or an expandable balloon.
 20. The system of claim 17, wherein the controller is configured to analyze the signal to map the passageway. 